Seattle Mariners, Luis Castillo agree to five-year, $108 million extension

Right-hander Luis Castillo and the Seattle Mariners are in agreement on a five-year contract extension that will keep the prized trade-deadline acquisition part of the ascendant team's core for the foreseeable future, the team announced on Saturday.

The deal is worth $108 million over the duration of the deal, sources told ESPN.

The contract, which includes a vesting option that could take its total value to $133 million, buys out four years of free agency for the 29-year-old, who has been dominant in eight starts since joining Seattle before the Aug. 2 trade deadline. In 54 innings, Castillo has struck out 64, walked 13 and allowed just five home runs with a 2.83 ERA -- even better than the…